Infants and young children are as likely as adults to have abnormalities of the visual system that produce visual field defects. Only recently have methods to assess peripheral field extent of infants been applied clinically. To date, testing of individual patients has been done with suprathreshold stimuli, limiting the field losses that can be detected to major, absolute field defects. The goal of this project is to broaden the types of visual field defects that can be tested in young patients, specifically, to develop tests that are sensitive to relative, central visual field losses as well as to peripheral defects. The forced-choice perimetry method, in which an adult judges stimulus direction based on the infant's eye movement, was developed using an LED perimeter with infants age 6 months and older. Because younger infants and patients with poor visual acuity cannot be tested with the LED perimeter, a new infant arc perimeter will be used. To accomplish the efficient testing that is necessary due to the short attention of infants, stimuli will be presented on four oblique meridia which avoids extraneous infant eye movements elicited by distracting stimuli and at near eccentricities (20, 40 deg) which does not tax the immature and unreliable infant oculomotor system. To determine optimal stimulus parameters for clinical tests, photopic increment thresholds of normal infants ages 10 to 40 weeks for stimuli varying in size will be studied. Efficient clinical procedures will be evaluated for their specificity using these stimulus values in the same ages. Children, ages 3 to 6 years, will be tested with the LED perimeter using the same design. It is expected that the different pediatric field tests will be sensitive and specific for different types of field defects. To evaluate this, patients with pre-chiasmal (retinal degeneration) and post-chiasmal or chiasmal lesions will be tested with the clinical perimetry methods. Age- related change in visual fields will be studied in individual patients. This project could provide a selection of tests appropriate for young patients at risk of different types of field loss over a wide age range. Potential clinical utility includes evaluating progresssive retinal disease, the effect of brain damage on the developing visual system, recovery from trauma and the effects of treatment. Moreover, pediatric field tests could significantly benefit the educational management of young, visually impaired patients.